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Elden [556K]
2 years ago
5

Describe why the periodic table needed to be reordered in 1913.

Chemistry
1 answer:
Norma-Jean [14]2 years ago
7 0

Answer:

1913. Henry Moseley determined the atomic number of each of the known elements. He realized that, if the elements were arranged in order of increasing atomic number rather than atomic weight, they gave a better fit within the 'periodic table'.

Explanation:

GOO

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Calculate the percent solute of 1.4g of NaCl in 46.6g of saline solution​
igomit [66]

Answer:

3.0%

Explanation:

A solution's mass percent concentration, (% m/m), is calculated by observing the mass of solute in grams of obtained in each 100 g of solution. In simple terms, the solution's mass percent concentration is given by the number of parts of solute obtained in every 100 parts of solution, made up of solute and solvent.

Hence the percent m/m concentration of a solution is obtained as;

Mass of solute/ mass of solution × 100/1

From the question, we have,

Mass of solute= 1.4g

Mass of solution= 46.6 g

Therefore, percent m/m concentration of the saline solution=

1.4/46.6 ×100/1 = 3.0%

The percent solute concentration of the solution is 3.0%

7 0
3 years ago
For the reaction PC15 (8) PC13 (g) + Cl2 (g) K = 0.0454 at 261 °C. If a vessel is filled with these gases such that the initial
Fiesta28 [93]

Answer:

The correct answer is B.

The K_{eq} is samller than Q of the reaction . So,the reaction will shift towards the left i.e. towards the reactant side.

Explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as K_{eq}

K is the constant of a certain reaction when it is in equilibrium, while Q is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.

For the given chemical reaction:

PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)

The expression for Q is written as:

Q=\frac{[PCl_3][Cl_2]}{[[PCl_5]^1}

Q=\frac{0.20 M\times 2.5 M}{0.20 M}

Q=2.5

Given : K_{eq} = 0.0454

Thus as K_{eq}, the reaction will shift towards the left i.e. towards the reactant side.

4 0
4 years ago
Read 2 more answers
A steel calorimeter has a volume of 75.0 mL and is charged with Oxygen gas to a
EastWind [94]

Answer:

7.78×10¯³ mole

Explanation:

From the question given above, the following data were obtained:

Volume (V) = 75 mL

Pressure (P) = 255 kPa

Temperature (T) = 22.5 °C

Number of mole (n) =?

Next, we shall convert 75 mL to L. This can be obtained as follow:

1000 mL = 1 L

Therefore,

75 mL = 75 mL × 1 L / 1000 mL

75 mL = 0.075 L

Next, we shall convert 22.5 °C to Kelvin temperature. This can be obtained as follow:

T(K) = T(°C) + 273

Temperature (T) = 22.5 °C

Temperature (T) = 22.5 °C + 273

Temperature (T) = 295.5 K

Finally, we shall determine the amount of oxygen molecules present in steel calorimeter. This can be obtained as follow:

Volume (V) = 0.075 L

Pressure (P) = 255 kPa

Temperature (T) = 295.5 K

Gas constant (R) = 8.314 KPa.L/Kmol

Number of mole (n) =?

PV = nRT

255 × 0.075 = n × 8.314 × 295.5

19.125 = n × 2456.787

Divide both side by 2456.787

n = 19.125 / 2456.787

n = 7.78×10¯³ mole

Thus, amount of oxygen molecules present in steel calorimeter is 7.78×10¯³ mole

7 0
3 years ago
What volume of methanol should be used to make 1.25 l of a 21.0 by volume solution
Nimfa-mama [501]
Answer:
262.5 mL

Explanation:
21% of 1.25 L volume is methanol, so the amount of methanol is,
0.21 × 1250 mL = 262.5 mL
6 0
3 years ago
Which of the following is a possible reason that urban sprawl is common even when it has a negative impact on the environment? a
Mrrafil [7]
<h2>Answer:</h2>

Option B is correct.

b. extending outward is more economical than extending upward

<h2>Explanation:</h2>

people tend to move from rural areas to urban for the greater facilities that they can enjoy at cities. This urban sprawl is also very economic because people will get more chances of jobs, business and work hence improving the economy.

6 0
3 years ago
Read 2 more answers
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